Retractable landing gear for airplanes



Feb. 14, 1939. R L 2,147,536

RETRACTABLE LANDING GEAR FOR AIRPLANES Filed Nov. 9, 1937 Patented Feb. 14, 1939 2,147,536

UNITED STATES PATENTOFFICE hen Lucien Levy, Montrohte (Seine), France, assignor to Socit dlnventions Aeronautiques g1. litliecaniques S. I. A. M., Fribourg, Switzer- Application November 9, 1937, Serial No. 173,693

In France November 10, 1936 1 Claim. (Cl. 60-52) The present invention relates to the systems of valve 6 being c1csed,the pump 1 is started. As retractable landing gear for airplanes, in which pointed out in the specification of said prior patthe action of a hydro-pneumatic energy accumucut, the lifting pressure acting in the pipes 3 and later is utilized for lowering the landing gear. 3a forces the piston oi. the jack V upwards (in the The invention is applicable, in particular, to case shown in the drawing), the effect of which 5 systems of this type which include a hydraulic is to increase the pressure in the accumulator 9, locking device and, inter alia, to the systems of the hydraulic locking device 8 then allowing liquid retractable landing gear for airplanes which are to pass from the chamber 1) into the accumulator described in applicants prior Patent No. 2,001,620. 9 as explained in said prior patent.

| The invention consists in providing the systems o the o m ow of the landing gear, 10

of airplane landing gear which utilize the action all t is e d d is f the D p the of a hydro-pneumatic energy accumulator for valve 6, so that the action of the accumulator and loweringthe landing gear, with an auxiliary-safethe r y causes h Piston 0f h J k V to ty device adapted to be brought into operation to s e i ensure the descent of the landing gear when the If, p a ra ture S ould Occur in the energy accumulated in the hydro-pneumatic ac- Pipe 30, or the accumulator 9 should, for any cumulator ceases accidentally to be available for reason, be unable t fu ti n, the Pilot p ns the that purpose, for example, in the event of a frac- 000k closes the 6001! T2 d Starts t D p 1 ture inthe pipe connecting said accumulator with Whilst actuating the ex aust valve 5. In these i t jack. circumstances, liquid under pressure is delivered 0 A combination of this auxiliary safety device into the Chamber the l D B e with the system described in the specification of valve 0, So tha e ot action of the p I said prior patent is represented diagrammatically, pplements gravity in r r to cause the landin the accompanying drawing which shows the 8 a to descend.

3 essential components of the earlier system, that It Will be understood that this Safety de ce is is t say; applicable to all systems of landing gearv in which A pump which draws t supply f mm; the action of a hydro-pneumatic accumulator is 2, a jack V for actuating the landing gear (not put into operati n for the des nt f said ear. shown), a hydro-pneumatic accumulator 9 whether said systems be, or be not provided with r municating with the jack v by way of a hydraulic a ra c ck device similar to t device 8, so

locking device 8 which is connected, through a, the function of which has been described in the pipe 3a, with the delivery pipe 3 between the pump Specification o said Prior P tand the jack V; a non-return valve 4 in said I m: pipe 3, and, finally, an exhaust valve 6 provided Actua'tihg System for retractable landing ear a in a pipe 5 branching from the delivery pipe 3. for p a es comp s a motive fl d pump, a

According to the present invention a branch 3d, hydraulic jack the like. a p for mal onfrom h delivery pipe 3 of th pump is adapted eration between said pump and one of the chamto place said pump in communication with the bers of J .ahydrc-pneumat1c accumulator. chamber 12' on the accumulator side of the jack a p between the other chamber of s d jack V, when the cock 1" provided on said pipe 3d, is and Said a um Safety P p branching Ofi 40 opened. Between the branching-off point a and from d normal Operatieh P p and nect ng the chamber 0 of the jack V is a second cock 1. the p p to the Other Chamber Of t jack, means The system arranged in this manner functions fer normally Placing Said Safety p p Out of the as follows: circuit of the pump, means for bringing said safe- Normally, the cock 1 is closed, and the cock r W P pe into Operation, nd an exhaustv pipe ,5

is open. branching of! from the normal operation pipe.

In order to raise the landinggear, the exhaust ENE UCIEN LEVY. 

